Exemplary embodiments pertain to the art of aircraft and, more particularly, to a touchdown orientation control system for a rotary wing aircraft.
A rotary wing aircraft include one or more rotors that provide lift, yaw control, and/or forward movement. More specifically, rotary wing aircraft include a main rotor assembly that provides lift and a tail rotor assembly that provides yaw control or, in the case of a propulsor, energy for forward movement. In some cases, both the main rotor assembly and the propulsor include dual rotor assemblies. The dual rotor assemblies may represent counter rotating rotors or co-rotating rotors.
Rotary wing aircraft typically descend for a touchdown along a desired path. The desired path typically includes a descent rate and may also include a forward component. Under certain conditions, a flight path of the rotary wing aircraft may attain an undesired lateral and/or rearward component. The lateral component may have resulted from input by a pilot or result from external forces such as air currents. In a degraded visual environment (DVE), the pilot is more susceptible to attaining undesired lateral and/or rearward components. Further, in a DVE, the pilot may not be aware of the existence of the undesired lateral and/or rearward components. Lateral and/or rearward landing/hover paths can result in a dynamic rollover condition or lead to undesirable contact with obstacles at or near the ground.